Moses g



(No Model.)

M. G. PARMER.

TELEPHONE TRANSMITTER. No. 380,427. Patented Apr. 3, 1888.

llNrrEn STATES PATENT Unmet.

MOSES G. FARMER, OF ELLIOT, MAINE.

TELEPHONE-TRANSM lTTER.

SPECIFICATION forming part of Letters Patent No. 330,427, dated April 3, 1888.

Application filed September 14, 1887. Serial No. 249,622. (No model.)

To all whom, it may concern:

Be it known that I, MOSES G. FARMER, a citizen of the United States, residing at Elliot, in the county of York, State of Maine, have invented a new and useful Improvement in TelephoneTransmitters, which improvement is fully set forth in the following specification and accompanying drawings.

My invention relates to improvements in telephone-transmitters of the I-Iunnings type; and it consists in a novel arrangement of the electrodes within the carbon powder, and in certain details of construction hereinafter de' scribed, and particularly pointed out in the claims which follow this specification.

In an application filed by me in the United States Patent Office April 14, 1887,- bearing Serial No. 234,795, I have disclosed a novel form oftelephone-transmitter of this type having rigid fixed electrodes, with a diaphragm sustaining the carbon powder against or upon the electrodes. In the invention I now propose to disclose I retain the carbon powder in trodes in close proximity to each other within the mass of loose powder.

My invention will be better understood by referring to the accompanying drawings, in which Figure l is a plan view of my improved telephone-transmitter with the diaphragm removed, so as to show the electrodes. Fig. 2 is a cross section on line a: as, Fig. 1. Fig. 3 is a plan view showing the diaphragm in place. Fig. 4 is an obverse plan view of the instru' ment, showing the connections and bindingposts.

Similar letters of reference indicate corresponding parts in the several figures.

Referring to the drawings, A is the body of the instrument, of gutta-percha or analogous material, ofcup form, as shown.

B B are two thin metal plates, the latter fitting snugly in the bottom of the cup and the former adapted to be held firmly in place over the carbon or comuiinuted powder, M, as shown, by the ring D, screw-threaded into the body of the instrument.

C O G O are four-perforated elastic metallic electrodes adapted to fit, as shown, the inner contour of the retaining-cup A, and held in place in the body of the carbon powder by the binding-screws N N, &e., havingmetal heads E E E E and metal washers II H, &c.

WV W are insulatingwashers, of mica or like material, adapted to insulate the plate B from the metal binding-posts connected to the electrodes O 0. Each pair of electrodes 0 G (3 O has a pair of metal washers, IV W", on the under side, connecting the electrodes electrically with the bindingposts N N and serving to sustain the electrodes in submerged condition in the comminuted powder, but insulated from the lower plate or diaphragm B by insulating washers, as shown.

N N are bindingposts, four in number, connected to the four electrodes E E E E and having binding-screws F F F F.

M is the commin'uted condnoting-powder, held in place by the diaphragm B and back plate B.

The electrodes are connected in pairs, E E being connected to the minus-pole of battery, as shown in Fig. 4, by wire or and bindingscrews F F, while E E are similarly connected to the plus pole by wire w and bindingscrews F F.

I find that with the metal front and back plates, both of which act as diaphragms, I increasethe conductibility of the instrument and get increased effects therefrom.

The retaining-ring D is secured in place by means of an instrument entering the holes 6 c.

Having thus described my inventiomwhat I claim as new, and desire to secure by Letters Patent, is-

1. A telephone-transmitter having comminuted powder retained between two conducting-plates, and two or more electrodes resting in the body of the powder between the plates, substantially as described.

2. A telephone-transmitter having two or more electrodes, in combination with front and back plates of conducting material, and carbon powder or analogous material located between said plates and entirely surrounding the electrodes, substantially as described.

3. The combination, in a telephone-transmitter, of a front and a back plate of conducting material, with two or more fixed perforated electrodes surrounded by carbon or analogous conducting-powder and located be tween the front and back plates, substantially as described.

4. In a telephone-transmitter, the combination of a retainingcase having aback plate of metal located inside said case, two or more electrodes entirely surrounded by carbon or analogous conducting-powder, and an additional metallic plate for holding the carbon powder in place, substantially as described.

5. In a telephone, a retaining case or cup, in combination with two metal plates, one located in the base of the cup and the other resting upon carbon powder contained in said cup, with two or more electrodes embedded in the carbon powder, and aretaining-ring adapted to hold the outer plate against the carbon powder, substantially as described.

6. In a telephone-transmitter, a non-conducting cup having two or more binding-posts rior, with two or more electrodes embedded in carbon powder located within said cup, with anexterior retaining metal plate, and a retaining-ring for holding said parts in connection, substantially as described.

MOSES G. FARMER.

Witnesses:

CHARLES E. FOYE, TIMOTHY DAME. 

